/*******************************************************************************
 * Copyright 2017 Bstek
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License.  You may obtain a copy
 * of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations under
 * the License.
 ******************************************************************************/
package com.bstek.ureport.expression.function.math;

import java.math.BigDecimal;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.bstek.ureport.build.Context;
import com.bstek.ureport.expression.model.data.ExpressionData;
import com.bstek.ureport.model.Cell;

/**
 * 求众数
 * 
 * @author Jacky.gao
 * @since 2017年1月23日
 */
public class ModeFunction extends MathFunction {

	@Override
	public Object execute(List<ExpressionData<?>> dataList, Context context, Cell currentCell) {
		int max = 0;
		BigDecimal result = null;
		List<BigDecimal> list = buildDataList(dataList);
		Map<Double, Integer> map = new HashMap<Double, Integer>();
		for (BigDecimal bigData : list) {
			if (bigData == null)
				continue;
			double d = bigData.doubleValue();
			if (map.containsKey(d)) {
				int count = map.get(d);
				count++;
				map.put(d, count);
				if (count > max) {
					max = count;
					result = bigData;
				}
			} else {
				map.put(d, 1);
				if (result == null) {
					max = 1;
					result = bigData;
				}
			}
		}
		return result;
	}

	@Override
	public String name() {
		return "mode";
	}
}
